Variable-rate compression springs for use in vehicle suspensions and comprising a rubbery body member surrounded by a fabric sleeve are disclosed in U.S. Pat. No. 3,892,398, issued July 1, 1975, to G. L. Marsh and assigned to the assignee of the present invention.
Conventionally, such springs have been produced by, for example, spirally winding an elastomer layer onto a mandrel to form the body, and then covering the exterior with a sheath of fabric-reinforced elastomer. Alternatively, after a rubber core is extruded, it may be mounted on a mandrel to receive a wound-on bias-cut fabric and outer cover, or it may later be assembled within a pre-prepared bias-fabric sleeve, before vulcanization in a mold. In order to improve quality, uniformity and productivity, the present process and apparatus have been designed.